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1 : : // Copyright (c) 2019-2022 The Bitcoin Core developers
2 : : // Distributed under the MIT software license, see the accompanying
3 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
4 : :
5 : : #include <util/asmap.h>
6 : :
7 : : #include <clientversion.h>
8 : : #include <logging.h>
9 : : #include <serialize.h>
10 : : #include <streams.h>
11 : : #include <util/fs.h>
12 : :
13 : : #include <algorithm>
14 : : #include <bit>
15 : : #include <cassert>
16 : : #include <cstdio>
17 : : #include <utility>
18 : : #include <vector>
19 : :
20 : : namespace {
21 : :
22 : : constexpr uint32_t INVALID = 0xFFFFFFFF;
23 : :
24 : 84634885 : uint32_t DecodeBits(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos, uint8_t minval, const std::vector<uint8_t> &bit_sizes)
25 : : {
26 : 84634885 : uint32_t val = minval;
27 : 84634885 : bool bit;
28 : 84634885 : for (std::vector<uint8_t>::const_iterator bit_sizes_it = bit_sizes.begin();
29 [ + - ]: 196677849 : bit_sizes_it != bit_sizes.end(); ++bit_sizes_it) {
30 [ + + ]: 196677849 : if (bit_sizes_it + 1 != bit_sizes.end()) {
31 [ - + ]: 175940897 : if (bitpos == endpos) break;
32 : 175913024 : bit = *bitpos;
33 : 175913024 : bitpos++;
34 : : } else {
35 : : bit = 0;
36 : : }
37 [ + + ]: 196649976 : if (bit) {
38 : 112042964 : val += (1 << *bit_sizes_it);
39 : : } else {
40 [ + + ]: 552828289 : for (int b = 0; b < *bit_sizes_it; b++) {
41 [ - + ]: 468295432 : if (bitpos == endpos) return INVALID; // Reached EOF in mantissa
42 : 468221277 : bit = *bitpos;
43 : 468221277 : bitpos++;
44 : 468221277 : val += bit << (*bit_sizes_it - 1 - b);
45 : : }
46 : : return val;
47 : : }
48 : : }
49 : : return INVALID; // Reached EOF in exponent
50 : : }
51 : :
52 : : enum class Instruction : uint32_t
53 : : {
54 : : RETURN = 0,
55 : : JUMP = 1,
56 : : MATCH = 2,
57 : : DEFAULT = 3,
58 : : };
59 : :
60 : : const std::vector<uint8_t> TYPE_BIT_SIZES{0, 0, 1};
61 : 42323363 : Instruction DecodeType(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
62 : : {
63 : 42323363 : return Instruction(DecodeBits(bitpos, endpos, 0, TYPE_BIT_SIZES));
64 : : }
65 : :
66 : : const std::vector<uint8_t> ASN_BIT_SIZES{15, 16, 17, 18, 19, 20, 21, 22, 23, 24};
67 : 21630749 : uint32_t DecodeASN(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
68 : : {
69 : 21630749 : return DecodeBits(bitpos, endpos, 1, ASN_BIT_SIZES);
70 : : }
71 : :
72 : :
73 : : const std::vector<uint8_t> MATCH_BIT_SIZES{1, 2, 3, 4, 5, 6, 7, 8};
74 : 10344704 : uint32_t DecodeMatch(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
75 : : {
76 : 10344704 : return DecodeBits(bitpos, endpos, 2, MATCH_BIT_SIZES);
77 : : }
78 : :
79 : :
80 : : const std::vector<uint8_t> JUMP_BIT_SIZES{5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30};
81 : 10336069 : uint32_t DecodeJump(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
82 : : {
83 : 10336069 : return DecodeBits(bitpos, endpos, 17, JUMP_BIT_SIZES);
84 : : }
85 : :
86 : : }
87 : :
88 : 15282302 : uint32_t Interpret(const std::vector<bool> &asmap, const std::vector<bool> &ip)
89 : : {
90 : 15282302 : std::vector<bool>::const_iterator pos = asmap.begin();
91 : 15282302 : const std::vector<bool>::const_iterator endpos = asmap.end();
92 : 15282302 : uint8_t bits = ip.size();
93 : 15282302 : uint32_t default_asn = 0;
94 : 15282302 : uint32_t jump, match, matchlen;
95 : 15282302 : Instruction opcode;
96 [ - + ]: 31781939 : while (pos != endpos) {
97 : 31781939 : opcode = DecodeType(pos, endpos);
98 [ + + ]: 31781939 : if (opcode == Instruction::RETURN) {
99 : 9666819 : default_asn = DecodeASN(pos, endpos);
100 [ - + ]: 9666819 : if (default_asn == INVALID) break; // ASN straddles EOF
101 : : return default_asn;
102 [ + + ]: 22115120 : } else if (opcode == Instruction::JUMP) {
103 : 6986520 : jump = DecodeJump(pos, endpos);
104 [ + - ]: 6986520 : if (jump == INVALID) break; // Jump offset straddles EOF
105 [ + - ]: 6986520 : if (bits == 0) break; // No input bits left
106 [ - + + - ]: 13973040 : if (int64_t{jump} >= int64_t{endpos - pos}) break; // Jumping past EOF
107 [ + + ]: 6986520 : if (ip[ip.size() - bits]) {
108 : 2413231 : pos += jump;
109 : : }
110 : 6986520 : bits--;
111 [ + + ]: 15128600 : } else if (opcode == Instruction::MATCH) {
112 : 9001800 : match = DecodeMatch(pos, endpos);
113 [ + - ]: 9001800 : if (match == INVALID) break; // Match bits straddle EOF
114 [ + - ]: 9001800 : matchlen = std::bit_width(match) - 1;
115 [ + - ]: 9001800 : if (bits < matchlen) break; // Not enough input bits
116 [ + + ]: 18185008 : for (uint32_t bit = 0; bit < matchlen; bit++) {
117 [ + + ]: 14798691 : if ((ip[ip.size() - bits]) != ((match >> (matchlen - 1 - bit)) & 1)) {
118 : : return default_asn;
119 : : }
120 : 9183208 : bits--;
121 : : }
122 [ + - ]: 6126800 : } else if (opcode == Instruction::DEFAULT) {
123 : 6126800 : default_asn = DecodeASN(pos, endpos);
124 [ + - ]: 6126800 : if (default_asn == INVALID) break; // ASN straddles EOF
125 : : } else {
126 : : break; // Instruction straddles EOF
127 : : }
128 : : }
129 : 0 : assert(false); // Reached EOF without RETURN, or aborted (see any of the breaks above) - should have been caught by SanityCheckASMap below
130 : : return 0; // 0 is not a valid ASN
131 : : }
132 : :
133 : 169888 : bool SanityCheckASMap(const std::vector<bool>& asmap, int bits)
134 : : {
135 [ + - ]: 169888 : const std::vector<bool>::const_iterator begin = asmap.begin(), endpos = asmap.end();
136 : 169888 : std::vector<bool>::const_iterator pos = begin;
137 : 169888 : std::vector<std::pair<uint32_t, int>> jumps; // All future positions we may jump to (bit offset in asmap -> bits to consume left)
138 [ + - ]: 169888 : jumps.reserve(bits);
139 : : Instruction prevopcode = Instruction::JUMP;
140 : : bool had_incomplete_match = false;
141 [ - + ]: 10552051 : while (pos != endpos) {
142 [ + + ]: 10541502 : uint32_t offset = pos - begin;
143 [ + + + + ]: 10541502 : if (!jumps.empty() && offset >= jumps.back().first) return false; // There was a jump into the middle of the previous instruction
144 : 10541424 : Instruction opcode = DecodeType(pos, endpos);
145 [ + + ]: 10541424 : if (opcode == Instruction::RETURN) {
146 [ + + ]: 3291516 : if (prevopcode == Instruction::DEFAULT) return false; // There should not be any RETURN immediately after a DEFAULT (could be combined into just RETURN)
147 : 3291123 : uint32_t asn = DecodeASN(pos, endpos);
148 [ + + ]: 3291123 : if (asn == INVALID) return false; // ASN straddles EOF
149 [ + + ]: 3287306 : if (jumps.empty()) {
150 : : // Nothing to execute anymore
151 [ - + + + ]: 10130 : if (endpos - pos > 7) return false; // Excessive padding
152 : 169888 : while (pos != endpos) {
153 [ + + ]: 9621 : if (*pos) return false; // Nonzero padding bit
154 [ + + - + ]: 13327 : ++pos;
155 : : }
156 : : return true; // Sanely reached EOF
157 : : } else {
158 : : // Continue by pretending we jumped to the next instruction
159 [ - + ]: 3282241 : offset = pos - begin;
160 [ + + ]: 3282241 : if (offset != jumps.back().first) return false; // Unreachable code
161 : 3282044 : bits = jumps.back().second; // Restore the number of bits we would have had left after this jump
162 : 3282044 : jumps.pop_back();
163 : 3282044 : prevopcode = Instruction::JUMP;
164 : : }
165 [ + + ]: 7249908 : } else if (opcode == Instruction::JUMP) {
166 : 3349549 : uint32_t jump = DecodeJump(pos, endpos);
167 [ + + ]: 3349549 : if (jump == INVALID) return false; // Jump offset straddles EOF
168 [ - + + + ]: 6667918 : if (int64_t{jump} > int64_t{endpos - pos}) return false; // Jump out of range
169 [ + + ]: 3282769 : if (bits == 0) return false; // Consuming bits past the end of the input
170 : 3282755 : --bits;
171 [ + + ]: 3282755 : uint32_t jump_offset = pos - begin + jump;
172 [ + + + + ]: 3282755 : if (!jumps.empty() && jump_offset >= jumps.back().first) return false; // Intersecting jumps
173 [ + - ]: 3282638 : jumps.emplace_back(jump_offset, bits);
174 : : prevopcode = Instruction::JUMP;
175 [ + + ]: 3900359 : } else if (opcode == Instruction::MATCH) {
176 : 1342904 : uint32_t match = DecodeMatch(pos, endpos);
177 [ + + ]: 1342904 : if (match == INVALID) return false; // Match bits straddle EOF
178 [ + - ]: 1337663 : int matchlen = std::bit_width(match) - 1;
179 [ + + ]: 1337663 : if (prevopcode != Instruction::MATCH) had_incomplete_match = false;
180 [ + + ]: 1337663 : if (matchlen < 8 && had_incomplete_match) return false; // Within a sequence of matches only at most one should be incomplete
181 : 1337550 : had_incomplete_match = (matchlen < 8);
182 [ + + ]: 1337550 : if (bits < matchlen) return false; // Consuming bits past the end of the input
183 : 1337523 : bits -= matchlen;
184 : 1337523 : prevopcode = Instruction::MATCH;
185 [ + + ]: 2557455 : } else if (opcode == Instruction::DEFAULT) {
186 [ + + ]: 2546124 : if (prevopcode == Instruction::DEFAULT) return false; // There should not be two successive DEFAULTs (they could be combined into one)
187 : 2546007 : uint32_t asn = DecodeASN(pos, endpos);
188 [ + + ]: 2546007 : if (asn == INVALID) return false; // ASN straddles EOF
189 : : prevopcode = Instruction::DEFAULT;
190 : : } else {
191 : : return false; // Instruction straddles EOF
192 : : }
193 : : }
194 : : return false; // Reached EOF without RETURN instruction
195 : 169888 : }
196 : :
197 : 0 : std::vector<bool> DecodeAsmap(fs::path path)
198 : : {
199 : 0 : std::vector<bool> bits;
200 [ # # ]: 0 : FILE *filestr = fsbridge::fopen(path, "rb");
201 [ # # ]: 0 : AutoFile file{filestr};
202 [ # # ]: 0 : if (file.IsNull()) {
203 [ # # ]: 0 : LogPrintf("Failed to open asmap file from disk\n");
204 : 0 : return bits;
205 : : }
206 [ # # ]: 0 : file.seek(0, SEEK_END);
207 [ # # ]: 0 : int length = file.tell();
208 [ # # # # ]: 0 : LogInfo("Opened asmap file %s (%d bytes) from disk", fs::quoted(fs::PathToString(path)), length);
209 [ # # ]: 0 : file.seek(0, SEEK_SET);
210 : : uint8_t cur_byte;
211 [ # # ]: 0 : for (int i = 0; i < length; ++i) {
212 [ # # ]: 0 : file >> cur_byte;
213 [ # # ]: 0 : for (int bit = 0; bit < 8; ++bit) {
214 [ # # ]: 0 : bits.push_back((cur_byte >> bit) & 1);
215 : : }
216 : : }
217 [ # # # # ]: 0 : if (!SanityCheckASMap(bits, 128)) {
218 [ # # # # ]: 0 : LogPrintf("Sanity check of asmap file %s failed\n", fs::quoted(fs::PathToString(path)));
219 : 0 : return {};
220 : : }
221 : 0 : return bits;
222 : 0 : }
223 : :
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